1. Field of the Invention
This invention relates to an apparatus for applying surgical fasteners, and more particularly to an apparatus for resection, transection and creation of anastomoses.
2. Background of the Art
Surgical fastening apparatus for resection, transection and creation of anastomoses are known in the art. For example, such apparatus are used for suturing gastric and intestinal walls with spaced parallel rows of longitudinally aligned surgical fasteners or staples. For example, U.S. Pat. No. 3,079,606 to Bobrov et al. discloses an instrument for suturing gastric and intestinal walls with metal staples by inserting the tips of the instrument through apertures in the walls of the organs to be sutured. The apparatus includes a two part frame with each part having a finger-like projection or fork. The forks are inserted respectively into the apertures in the walls of the organs to be sutured. The frame parts are hinged together with the body tissue held between the forks. When the instrument is actuated, or "fired", longitudinally moving cam bars contact staple drive members in one of the forks, thereby pushing the surgical staples through the body tissue and into an anvil in the opposite fork by which they are crimped closed. A knife blade between the cam bars creates an incision between the parallel rows of staples. It should be noted, however, that the knife blade is an optional feature, i.e. the instrument may be used to fasten body tissue without creating an incision between the rows of staples.
U.S. Pat. No. 3,490,675 to Green et al. discloses an improvement on the instrument discussed above, whereby a double row of staples is placed on each side of the incision.
A further improvement in this type of instrument is disclosed in U.S. Pat. No. 3,499,591 to Green, which incorporates an improved structure for the staple carrying cartridge, the pusher assembly which includes the cam bars and the knife, and the staple drive members.
Generally, the above mentioned instruments are successfully used in abdominal, gynecological, pediatric and thoracic surgery for resection, transection, and creation of anastomoses. Surgical fastener applying apparatus can be used to apply metal staples, which are crimped in the anvil portion of the apparatus, or bioabsorbable fasteners, such as two-part fasteners having a fastener portion and a retainer which interlocks therewith upon firing of the instrument. In any such instrument it is important to maintain proper alignments: alignment of the jaws of the instrument, and alignment of the tissue held between the jaws.
Alignment of the instrument jaws insures that the surgical fasteners are properly closed. In the case of metal staples, the staples are closed when their legs are crimped in corresponding depressions in the anvil. With respect to the two-part fasteners, the fastener portions must be properly aligned with the corresponding retainer portions in the anvil assembly so that closure, or interlocking can be achieved.
Tissue alignment insures that the instrument operates on the proper area of tissue. Such instruments, of course, are employed on various thicknesses of tissue. However, thinner tissue may have a tendency to become misaligned by shifting within the closed instrument. The possibility of such misalignment of tissue is increased by the presence of body fluids, such as blood, which tend to make the tissue slippery. On the other hand, an instrument whose jaws close firmly on thin tissue to prevent its misalignment might pinch the tissue, particularly thicker tissue.
One method which has been employed to preserve alignment of the instrument jaws is to use positioning buttons or projections on the lateral edges of the cartridge. These projections guide the anvil portion into proper alignment with the staple cartridge when the jaws of the instrument are closed. Under some circumstances, however, such projections can act as pinch points for tissue.
An improvement has now been developed for maintaining alignment of both the jaws of the instrument and the tissue between the jaws, without causing pinching of the tissue. Furthermore, various tissue thicknesses are automatically accommodated between the instrument jaws.